Method and system for measuring torque in a tiltrotor aircraft

ABSTRACT

A method for calculating torque through a rotor mast of a propulsion system of a tiltrotor aircraft includes receiving the torque being applied through a quill shaft of the rotorcraft. The quill shaft is located between a fixed gearbox and a spindle gearbox, and the spindle gearbox is rotatable about a conversion access. The torque through the rotor mast is determined by using the torque through the quill shaft and the efficiency loss value between the quill shaft and the rotor mast.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to and is a continuation patentapplication of U.S. patent application Ser. No. 14/526,621, filed Oct.29, 2014, which is hereby incorporated by reference for all purposes asif fully set forth herein.

BACKGROUND Technical Field

The present disclosure relates to measuring torque in a tiltrotoraircraft. The present disclosure also relates to a fixed engine androtating proprotor arrangement for a tiltrotor aircraft.

Description of Related Art

There are several different methods of measuring the torque in atiltrotor aircraft. A conventional method of measuring torque in atiltrotor aircraft is to apply sensors on the mast itself or on theengine output shaft of the tiltrotor aircraft. However, both of theseconventional methods have significant shortcomings. Therefore, there isa need for an alternative location to place a torque measuring system.

DESCRIPTION OF THE DRAWINGS

The novel features believed characteristic of the method and apparatusof the present disclosure are set forth in the appended claims. However,the method and apparatus itself, as well as a preferred mode of use, andfurther objectives and advantages thereof, will best be understood byreference to the following detailed description when read in conjunctionwith the accompanying drawings, wherein:

FIG. 1 is a perspective view of a tiltrotor aircraft in helicopter mode,according to one example embodiment;

FIG. 2 is a perspective view of a tiltrotor aircraft in airplane mode,according to one example embodiment;

FIG. 3 is a perspective view of a tiltrotor aircraft in airplane mode,according to one example embodiment;

FIG. 4 is a partial perspective view of a propulsion system portion ofthe tiltrotor aircraft, according to one example embodiment;

FIG. 5 is a cross-sectional view of a proprotor of the propulsionsystem, according to one example embodiment;

FIG. 6 is a partial perspective view of a propulsion system portion ofthe tiltrotor aircraft, according to one example embodiment;

FIG. 7 is a partial top view of the tiltrotor aircraft, according to oneexample embodiment;

FIG. 8 is a partial perspective view of the tiltrotor aircraft,according to one example embodiment;

FIG. 9 is a partial perspective view of the tiltrotor aircraft,according to one example embodiment;

FIG. 10 is a cross-sectional view of the propulsion system, according toone example embodiment;

FIG. 11 is a cross-sectional view of the propulsion system, according toone example embodiment;

FIG. 12 is a perspective view of a quill shaft, according to one exampleembodiment;

FIG. 13 is a perspective view of the propulsion system in a partiallydisassembled state, according to one example embodiment;

FIG. 14 is a perspective view of the propulsion system in a partiallydisassembled state, according to one example embodiment;

FIG. 15 is a schematic of a torque measuring system according to oneexample embodiment;

FIG. 16 is a schematic of a torque measuring system according to oneexample embodiment; and

FIG. 17 is a schematic of a computer system according to one exampleembodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Illustrative embodiments of the method and apparatus of the presentdisclosure are described below. In the interest of clarity, all featuresof an actual implementation may not be described in this specification.It will of course be appreciated that in the development of any suchactual embodiment, numerous implementation-specific decisions must bemade to achieve the developer's specific goals, such as compliance withsystem-related and business-related constraints, which will vary fromone implementation to another. Moreover, it will be appreciated thatsuch a development effort might be complex and time-consuming but wouldnevertheless be a routine undertaking for those of ordinary skill in theart having the benefit of this disclosure.

In the specification, reference may be made to the spatial relationshipsbetween various components and to the spatial orientation of variousaspects of components as the devices are depicted in the attacheddrawings. However, as will be recognized by those skilled in the artafter a complete reading of the present disclosure, the devices,members, apparatuses, etc. described herein may be positioned in anydesired orientation. Thus, the use of terms such as “above,” “below,”“upper,” “lower,” or other like terms to describe a spatial relationshipbetween various components or to describe the spatial orientation ofaspects of such components should be understood to describe a relativerelationship between the components or a spatial orientation of aspectsof such components, respectively, as the device described herein may beoriented in any desired direction.

Referring to FIGS. 1 and 2 in the drawings, a tiltrotor aircraft 101 isillustrated. Tiltrotor aircraft 101 can include a fuselage 103, alanding gear 105, a tail member 107, a wing 109, a propulsion system111, and a propulsion system 113. Each propulsion system 111 and 113includes a fixed engine and a rotatable proprotor 115 and 117,respectively. Each rotatable proprotor 115 and 117 have a plurality ofrotor blades 119 and 121, respectively, associated therewith. Theposition of proprotors 115 and 117, as well as the pitch of rotor blades119 and 121, can be selectively controlled in order to selectivelycontrol direction, thrust, and lift of tiltrotor aircraft 101.

FIG. 1 illustrates tiltrotor aircraft 101 in helicopter mode, in whichproprotors 115 and 117 are positioned substantially vertical to providea lifting thrust. FIG. 2 illustrates tiltrotor aircraft 101 in anairplane mode, in which proprotors 115 and 117 are positionedsubstantially horizontal to provide a forward thrust in which a liftingforce is supplied by wing 109. It should be appreciated that tiltrotoraircraft can be operated such that proprotors 115 and 117 areselectively positioned between airplane mode and helicopter mode, whichcan be referred to as a conversion mode.

The propulsion system 113 is substantially symmetric to the propulsionsystem 111; therefore, for sake of efficiency certain features will bedisclosed only with regard to propulsion system 111. However, one ofordinary skill in the art would fully appreciate an understanding ofpropulsion system 113 based upon the disclosure herein of propulsionsystem 111.

Further, propulsion systems 111 and 113 are illustrated in the contextof tiltrotor aircraft 101; however, propulsion systems 111 and 113 canbe implemented on other tiltrotor aircraft. For example, an alternativeembodiment may include a quad tiltrotor that has an additional wingmember aft of wing 109, the additional wing member can have additionalpropulsion systems similar to propulsion systems 111 and 113. In anotherembodiment, propulsion systems 111 and 113 can be used with an unmannedversion of tiltrotor aircraft 101. Further, propulsion systems 111 and113 can be integrated into a variety of tiltrotor aircraftconfigurations.

Referring now also to FIGS. 3-11, propulsion system 111 is disclosed infurther detail. Propulsion system 111 includes an engine 123 that isfixed relative to wing 109. An engine output shaft 125 transfers powerfrom engine 123 to a spiral bevel gearbox 127 that includes spiral bevelgears to change torque direction by 90 degrees from engine 123 to afixed gearbox 129 via a clutch. Fixed gearbox 129 includes a pluralityof gears, such as helical gears, in a gear train that are coupled to aninterconnect drive shaft 131, and a quill shaft 203. Torque istransferred to an input 167 in spindle gearbox 133 of proprotor gearbox147 through the quill shaft 203.

The interconnect drive shaft 131 provides a torque path that enables asingle engine to provide torque to both proprotors 111 and 113 in theevent of a failure of the other engine. In the illustrated embodiment,interconnect drive shaft 131 has a rotational axis 135 that isvertically lower and horizontally aft of the conversion axis 137 of thespindle gearbox 133. Conversion axis 137 is parallel to a lengthwiseaxis 225 of wing 109. Referring in particular to FIG. 8, interconnectdrive shaft 131 includes a plurality of segments that share a commonrotational axis 135. Location of interconnect drive shaft 131 aft of theaft wing spar 197 provides for optimal integration with fixed gearbox129 without interfering with the primary torque transfer in the quillshaft 203 between fixed gearbox 129 and spindle gearbox 133; as such,the conversion axis 137 of spindle gearbox 133 is parallel to therotational axis 135 and interconnect drive shaft 131, but locatedforward and above rotational axis 135.

Engine 123 can be housed and supported in an engine nacelle 139. Enginenacelle 139 can include an inlet 141, aerodynamic fairings, and exhaust,as well as other structures and systems to support and facilitate theoperation of engine 123.

The proprotor 115 of propulsion system 111 can include a plurality ofrotor blades 119 coupled to a yoke 143. The yoke 143 can be coupled to amast 145. Mast 145 is coupled to a proprotor gearbox 147. It should beappreciated that proprotor 115 can include other components, such as aswashplate 149 that is selectively actuated by a plurality of actuators151 to selectively control the pitch of rotor blades 119 via pitch links153.

Proprotor gearbox 147 is configured to transfer power and reduce speedto mast 145. Further, proprotor gearbox 147 provides operational supportof proprotor 115. Referring in particular to FIG. 5, proprotor gearbox147 can include a top case 155 portion and spindle gearbox 133. Speedreduction is accomplished by a low speed planetary gear assembly 159 anda high speed planetary gear assembly 161. A spiral bevel gear assembly163 includes a spiral bevel gear input 167 and a spiral bevel gearoutput 171. Spiral bevel gear assembly 163 changes power direction fromalong a centerline axis 165 of spiral bevel gear input 167 to acenterline axis 169 of spiral bevel gear output 171. An accessory drive173 can be coupled to spiral bevel gear output 171. It should beappreciated that proprotor gearbox 147 can include any bearings,lubrication systems, and other gearbox related components that may bebeneficial for operation.

During operation, a conversion actuator 175 (shown at least in FIG. 4)can be actuated so as to selectively rotate proprotor gearbox 147 abouta conversion axis 137 that corresponds with axis 165, which in turnselectively positions proprotor 115 between helicopter mode (shown inFIG. 1) and airplane mode (shown in FIG. 2). The operational loads, suchas thrust loads, are transmitted through rotor mast 145 and into thespindle gearbox 133 of proprotor gearbox 147, and thus the structuralsupport of spindle gearbox 133 is critical.

In the illustrated embodiment, the spindle gearbox 133 of proprotorgearbox 147 is mounted to an inboard pillow block 181 with an inboardbearing assembly 177. Similarly, spindle gearbox 133 of proprotorgearbox 147 is mounted to an outboard pillow block 183 with an outboardbearing assembly 179. Thus, spindle gearbox 133 is structurallysupported but rotatable about conversion axis 137 by conversion actuator175. Inboard pillow block 181 is structurally coupled to an inboard rib185. Similarly, outboard pillow block 183 is structurally coupled to anoutboard rib 187. In one embodiment, an inboard intermediate support 189is utilized as a structural element between inboard pillow block 181 andinboard rib 185, and an outboard intermediate support 191 is similarlyutilized as a structural element between outboard pillow block 183 andoutboard rib 187. It should be appreciated that the exact structuralconfiguration is implementation specific, and that structural componentscan be combined and/or separated to meet implementation specificrequirements.

Spindle gearbox 133 of proprotor gearbox 147 is located above a surfaceof an upper wing skin 193 at a distance D1 (shown in FIG. 11), whilealso being approximately centered between inboard rib 185 and outboardrib 187. One advantage of locating the proprotor gearbox 147 above thesurface of upper wing skin 193 is that the fore/aft location ofproprotor gearbox 147 can be easily tailored to align the aircraftcenter of gravity (CG) with the conversion axis 137 while the propulsionsystem 111 is in helicopter mode, while also aligning the aircraftcenter of gravity (CG) with the wing aerodynamic center of lift whilethe propulsion system 111 is in airplane mode. Because the aircraftcenter of gravity (CG) shifts as the proprotor 115 rotates betweenhelicopter mode and airplane mode, the distance from the location ofproprotor 115 in helicopter mode and airplane mode center of lift mustcorrespond. As such, locating proprotor gearbox 147 above the wingallows the exact fore/aft location to be optimized accordingly, whilealso structurally attaching the proprotor gearbox 147 with in a zone ofthe torque box formed by forward wing spar 195, aft wing spar 197,inboard rib 185, and outboard rib 187.

The location of the spindle gearbox 133 portion of proprotor gearbox 147provides an efficient structural support for enduring operational loadsby being mounted to inboard rib 185 and outboard rib 187, which togetherwith a forward wing spar 195 and an aft wing spar 197, form a structuraltorque box. For example, when aircraft 101 is in helicopter mode, torqueabout mast axis 169 is reacted by the torque box collectively formed byinboard rib 185, outboard rib 187, forward wing spar 195, and aft wingspar 197. It should be noted that location of spindle gearbox 133 ofproprotor gearbox 147 also positions the mast axis 169, while inhelicopter mode, inboard of outboard rib 187, outboard of inboard rib185, forward of aft spar 197, and aft of forward spar 195, which allowsthe axis of the torque to be inside of the torque box structure, ratherthan cantilevered outside of the torque box structure. In contrast, aspindle gearbox location outside (such as outboard, forward, or aft)would cause a moment that would increase operational loading, thusrequiring heavier and less efficient structural support.

Fixed gearbox 129 is secured to outboard pillow block 183 with a housing199. Housing 199 is a conical structure with one or more flangesconfigured for coupling to gearbox 129 and outboard pillow block 183. Anadditional support may be utilized to provide additional support betweengearbox 129 and the wing structure, such as supplemental support 201(shown in FIG. 9); however, housing 199 is the primary support structuretherebetween. In one embodiment, supplemental support 201 is strong inthe inboard/outboard and vertical directions, but weak in the fore/aftdirection. Housing 199 is significant because it is configured tominimize misalignment between fixed gearbox 129 and spindle gearbox 133.If the primary attachment structure was not common with the attachmentstructure of proprotor gearbox 147, then operation loading, such as loaddeflection and/or thermal growth, would dramatically increase themisalignment therebetween.

Power is transferred from fixed gearbox 129 to spindle gearbox 133 ofproprotor gearbox 147 through the quill shaft 203. Quill shaft 203 is afloating shaft configured to accept any misalignment due tomanufacturing tolerances and operational effects between the fixedsystem (fixed gearbox 129) and the rotating system (proprotor gearbox147). Quill shaft 203 is configured to be assembled and disassembledindependently from the fixed and rotating systems. As such, quill shaft203 can be removed without removing either of the fixed and rotatingsystems.

Referring also to FIGS. 12-14, quill shaft 203 can have a first splinedportion 205 and a second splined portion 207. In the illustratedembodiment, the first splined portion 205 has a smaller diameter thanthe second splined portion 207, thus the first splined portion 205 islocated inboard and the second splined portion 207 is located outboardso that the quill shaft 203 can be removed to the outboard direction forinspection/maintenance thereof. Quill shaft 203 can include one or moreinboard lubrication ports 209 and outboard lubrication ports 211. Quillshaft 203 can also include a first sect of o-ring glands 213 and asecond set of o-ring glands 215.

During operation, second splined portion 207 is in torque engagementwith an output gear 217 of fixed gearbox 129 while first splined portion205 is in torque engagement with a splined portion of the input 167 tospindle gearbox 133. The first splined portion 205 and second splinedportion 207 are crowned to promote teeth engagement in the event ofnon-axial misalignment between spindle gearbox 133 and fixed gearbox129. Lubrication oil is circulated to the mating surfaces of the firstsplined portion 205 through outboard lubrication ports 211, the sealsassociated with the second set of o-ring glands forcing the lubricationfluid to flow to the first splined portion 205 instead of flowing towardthe center of quill shaft 203. Similarly, lubrication oil is circulatedto the mating surfaces of the second splined portion 207 through inboardlubrication ports 209, the seals associated with the first set of o-ringglands forcing the lubrication fluid to flow to the second splinedportion 207 instead of flowing toward the center of quill shaft 203.

One unique aspect of the configuration of quill shaft 203 in conjunctionwith spindle gearbox 133 and fixed gearbox 129 is that quill shaft 203can be removed without removing either of the spindle gearbox 133 andfixed gearbox 129. An access cover 219 can be removed thereby accessingthe second splined portion 207 of quill shaft 203. An interior portion221 includes a feature, such as threads, for which a removal tool 223can attach thereto. In one embodiment, interior portion 221 has femalethreads, while removal tool 223 has male threads that mate thereto. Uponattachment of removal tool 223 to quill shaft 203, the quill shaft 203can be removed by pulling out in an outboard direction along thecenterline axis of the quill shaft 203. Quill shaft 203 is critical forthe operation of aircraft 101, as such, safety and efficiency ofoperation is improved by increasing the ease for which quill shaft 203can be inspected.

The embodiments disclosed herein provide one or more of the followingadvantages. For example, the location and orientation of proprotor inrelation to the wing structure enables the proprotor to be adequatelysupported with minimal structural mass, while also providing efficientmaintainability. Location of the proprotor above the wing allows theproprotor to be removed in an upward direction upon removing the quillshaft, as such, the fixed gearbox and engine don't have to be removed ordisassembled when a maintenance action only requires servicing of theproprotor.

Further advantages include a quill shaft located between the fixedgearbox and a rotating spindle gearbox of the proprotor that allows formisalignment between the two. For example, the splined portions of thequill shaft allow for axial translation or floating in relation to themating features on the fixed gearbox and the spindle gearbox, such aswhen operation of the tiltrotor causes misalignment in the axialdirection of the quill shaft. Further, the splined portions on the quillshaft can be crowned to further allow for non-axial misalignment, suchas fore/aft misalignment. Further, quill shaft is configured to beeasily removed during a maintenance and/or inspection procedure.

The configuration of propulsion system 111, specifically the easilyremovable quill shaft 203 between the fixed gearbox 129 and the rotatingspindle gearbox 133, lends itself to a unique placement of severaldifferent types of torque sensors. The unique placement of the torquesensors is to locate them in a way to measure torque through quill shaft203.

Conventionally, torque sensors have been used to measure the torquethrough a mast of an aircraft, such as tiltrotor aircraft 101, orthrough the engine output shaft. However, both of these methods havesignificant shortcomings that are solved by relocating the torquesensors to measure torque through quill shaft 203.

One of the disadvantages of measuring torque through the mast of anaircraft is that if the torque sensors on the mast fail, the mast wouldneed to be removed from the aircraft in order to replace the torquesensors. Removing and reinstalling the mast from the aircraft is veryexpensive and very time consuming. Further, the size and torque of themast contributes to a high cost for sensor calibration. Since quillshaft 203 is easily removable and comparatively small in size and torquecapacity, placing the sensors to measure the torque through quill shaft203 solves this problem.

Another disadvantage of applying the torque sensors to the mast is thatthe mast goes into a gearbox. One of the preferred methods of sensingtorque through a mast uses magnetic sensors to detect a change in amagnetic field due to torque or a physical change in position betweentwo targets. Since the mast is partially inside a gearbox, it would bepossible for metal debris to be attracted to the magnetic sensors or themagnetized portions on the mast. This is unfavorable because the chipdetector could be compromised if the metal debris is attracted to themagnetic components instead of the chip detector. Since quill shaft 203is not located inside a gearbox, locating the torque sensors to measuretorque through quill shaft 203 does not have the issue of attractingmetal debris from inside the gearboxes.

One of the disadvantages of measuring torque through the engine outputshaft of an aircraft, such as tiltrotor aircraft 101, is that it wouldbe necessary that the torque loads required to power the accessories arecalculated during operation to most accurately estimate the torquethrough the mast. The reason why it would be necessary to measure thetorque loads required to power the accessories is because theaccessories are located downstream from the engine output shafts, butupstream from the mast. There are different types of accessories thatcan draw power from the system. These accessories can includealternators, lube and scavenge pumps, hydraulic pumps, and generators.In one embodiment, the accessory drives are located in the gear trainwithin fixed gearbox 129 (shown at least in FIG. 13). The torque loadabsorbed by these accessories would fluctuate significantly, dependingon the operation of the aircraft. However, on a system that is limitedby mast torque, the data processing system would have to assume that theaccessories are running at full capacity and are draining maximum power,all the time. On an aircraft that is limited by mast torque, thisassumption would artificially limit the mast torque lower than necessaryand reduce overall aircraft performance. In contrast, since quill shaft203 is located downstream from the accessories, measuring torque throughquill shaft 203 is more accurate and provides significant advantages.

Another disadvantage of measuring torque through the engine output shaftis that if one of the engines fail, accurately measuring torque would bedifficult. For example, if engine 123 were to fail, engine output shaft125 would no longer have torque running through it. However, if thetorque measuring system were on quill shaft 203, the interconnect driveshaft 131 would transfer torque from the remaining engine, to fixedgearbox 129, then to quill shaft 203. Since the torque measuring systemis on quill shaft 203, you would still be able to calculate torque ifengine 123 were to fail.

Now referring to FIG. 15, a simplified schematic of one exampleembodiment of a torque measuring system, magnetic torque sensor system500, is shown. Magnetic torque sensor system 500 can include any deviceor devices operable to measure torque through quill shaft 203. Forexample, magnetic torque sensor system 500 can includemagnetoelastically active elements 504 and sensors 506, which aresimilar to the invention disclosed in U.S. Pat. No. 4,896,544, which ishereby incorporated by reference.

Magnetoelastically active elements 504 can be any objects or materialsthat experience the Villari Effect. The Villari Effect is the phenomenonthat occurs when magnetoelastic materials are distorted or twisted. Whenmagnetoelastic materials are twisted, a change in the direction andstrength of the magnetic field occurs. The change in the direction andstrength of the magnetic field creates a current and can be detected bytransducers, such as sensors 506. The change in the direction andstrength of the magnetic field can be used to calculate the torquethrough quill shaft 203. Sensors 506 can represent any device that hasthe capability to detect a magnetic field or current produced bymagnetoelastically active elements 504. For example, sensors 506 can beHall Effect sensors.

Persons of ordinary skill in the art would appreciate that there areseveral methods of applying magnetoelastically active elements 504 toquill shaft 203. Methods would include, but are not limited to, affixingamorphous ribbons onto quill shaft 203, and plasma spraying orelectrodeposition of magnetic metals onto quill shaft 203.

Magnetoelastically active elements 504 can be oppositely polarized andcan span the entire circumference of quill shaft 203. Additionally,magnetoelastically active elements 504 can be applied to quill shaft 203prior to installation and can be placed at a location so that themagnetized portion is within housing 199.

Magnetic torque sensor system 500 can also include two pairs of sensors506, which can be placed in close proximity to magnetoelastically activeelements 504. Sensors 506 may not make physical contact with quill shaft203, but may be within range to read changes in the magnetic field ofmagnetoelastically active elements 504. Additionally, the sensors 506can be placed far enough from quill shaft 203 in order to accommodatefor shaft misalignment or small lateral translations of quill shaft 203.Persons of ordinary skill in the art would appreciate that magnetictorque sensor system 500 can be accomplished with one magnetoelasticactive element 504 and one sensor 506.

Now referring to FIG. 16, a simplified schematic of another exampleembodiment of a torque measuring system, a phase shift system 600 isshown. Phase shift system 600 uses a method which is similar to thesystem and method disclosed in U.S. Pat. No. 8,132,474, which is herebyincorporated by reference. Phase shift system 600 can include stand pipe606, which can be connected to the first portion 608 of quill shaft 203in such a way that when quill shaft 203 rotates, stand pipe 606 rotatesas well. Any torsional deflection experienced by first portion 608 isalso, proportionally, experienced by stand pipe 606. Stand pipe 606 canbe coupled to first magnet 612, such that when stand pipe 606 rotates,first magnet 612 rotates at the same velocity as stand pipe 606. Thiscauses first magnet 612 to rotate at the same velocity as stand pipe606, which rotates at the same velocity as first portion 608 of quillshaft 203. In this manner, first magnet 612 is referenced to firstportion 608 of quill shaft 203. A second magnet 614 is coupled to asecond portion 610 of quill shaft 203. In this manner, second magnet 614is referenced to second portion 610 of quill shaft 203. Magnets 612 and614 can be any object that creates a magnetic field.

In one example embodiment, magnets 612 and 614 can be placed 180 degreesapart from each other on the same plane. As quill shaft 203 and standpipe 606 rotate, magnets 612 and 614 are rotated past sensors 602 and604. Sensors 602 and 604 represent any device that has the capability todetect a magnetic field or current produced by magnets 612 and 614. Forexample, sensors 602 and 604 can be a Hall Effect transducer to sensethe magnetic field of each magnet 612 and 614. It should be understoodthat magnets 612 and 614 do not need to be separated from each other by180 degrees. Indeed, magnets 612 and 614 can be offset from each otherby any desirable amount.

When torque is transferred from the engine to quill shaft 203, thetorque causes a torsional twisting of quill shaft 203. Stand pipe 606,being coupled to the first portion 608 of quill shaft 203, follows therotational twist of first portion 608. This torsional twisting of quillshaft 203 causes a rotational lag between first portion 608 of quillshaft 203 and second portion 610 of quill shaft 203. This rotational lagresults in a phase shift between magnets 612 and 614, which is detectedby sensor 602. The torque through quill shaft 203 can then be calculatedfrom the phase shift between magnets 612 and 614.

Referring now to FIG. 17, sensors 506 in magnetic torque sensor system500 or sensors 602 and 604 in phase shift system 600 can be connected toa computer system 10. The computer system 10 may receive input fromsensors 506, or sensors 602 and 604, and may calculate the torque inquill shaft 203. The computer system 10 may also calculate the torque inmast 145 by accounting for torque loss from quill shaft 203 to mast 145.Computer system 10 may calculate the torque being applied to mast 145 bycompensating for levels of efficiency losses between quill shaft 203 andmast 145. For example, computer system 10 may use a calculatedefficiency loss factor or use a table of efficiency loss factors. Thecalculated efficiency loss factors can be determined by analyticalanalysis of actual measurement of various parameters which are obtainedbeforehand.

Computer system 10 can also be configured for performing one or morefunctions with regard to the operation of magnetic torque sensor system500 or phase shift system 600. Further, any processing and analysis canbe partly or fully performed by computer system 10. Computer system 10can be partly or fully integrated with other aircraft computer systems.

The system 10 can include an input/output (I/O) interface 12, ananalysis engine 14, and a database 16. Alternative embodiments cancombine or distribute the input/output (I/O) interface 12, analysisengine 14, and database 16, as desired. Embodiments of the system 10 caninclude one or more computers that include one or more processors andmemories configured for performing tasks described herein. This caninclude, for example, a computer having a central processing unit (CPU)and non-volatile memory that stores software instructions forinstructing the CPU to perform at least some of the tasks describedherein. This can also include, for example, two or more computers thatare in communication via a computer network, where one or more of thecomputers include a CPU and non-volatile memory, and one or more of thecomputer's non-volatile memory stores software instructions forinstructing any of the CPU(s) to perform any of the tasks describedherein. Thus, while the exemplary embodiment is described in terms of adiscrete machine, it should be appreciated that this description isnon-limiting, and that the present description applies equally tonumerous other arrangements involving one or more machines performingtasks distributed in any way among the one or more machines. It shouldalso be appreciated that such machines need not be dedicated toperforming tasks described herein, but instead can be multi-purposemachines, for example computer workstations, that are suitable for alsoperforming other tasks.

The I/O interface 12 can provide a communication link between externalusers, systems, and data sources and components of the system 10. TheI/O interface 12 can be configured for allowing one or more users toinput information to the system 10 via any known input device. Examplescan include a keyboard, mouse, touch screen, and/or any other desiredinput device. The I/O interface 12 can be configured for allowing one ormore users to receive information output from the system 10 via anyknown output device. Examples can include a display monitor, a printer,cockpit display, and/or any other desired output device. The I/Ointerface 12 can be configured for allowing other systems to communicatewith the system 10. For example, the I/O interface 12 can allow one ormore remote computer(s) to access information, input information, and/orremotely instruct the system 10 to perform one or more of the tasksdescribed herein. The I/O interface 12 can be configured for allowingcommunication with one or more remote data sources. For example, the I/Ointerface 12 can allow one or more remote data source(s) to accessinformation, input information, and/or remotely instruct the system 10to perform one or more of the tasks described herein.

The database 16 provides persistent data storage for system 10. Whilethe term “database” is primarily used, a memory or other suitable datastorage arrangement may provide the functionality of the database 16. Inalternative embodiments, the database 16 can be integral to or separatefrom the system 10 and can operate on one or more computers. Thedatabase 16 preferably provides non-volatile data storage for anyinformation suitable to support the operation of magnetic torque sensorsystem 500 and phase shift system 600, including various types of data.The analysis engine 14 can include various combinations of one or moreprocessors, memories, and software components.

The particular embodiments disclosed herein are illustrative only, asthe system and method may be modified and practiced in different butequivalent manners apparent to those skilled in the art having thebenefit of the teachings herein. Modifications, additions, or omissionsmay be made to the system described herein without departing from thescope of the invention. The components of the system may be integratedor separated. Moreover, the operations of the system may be performed bymore, fewer, or other components.

Furthermore, no limitations are intended to the details of constructionor design herein shown, other than as described in the claims below. Itis therefore evident that the particular embodiments disclosed above maybe altered or modified and all such variations are considered within thescope and spirit of the disclosure. Accordingly, the protection soughtherein is as set forth in the claims below.

To aid the Patent Office, and any readers of any patent issued on thisapplication in interpreting the claims appended hereto, applicants wishto note that they do not intend any of the appended claims to invokeparagraph 6 of 35 U.S.C. § 112 as it exists on the date of filing hereofunless the words “means for” or “step for” are explicitly used in theparticular claim.

The invention claimed is:
 1. A method of operating a tiltrotor aircraft,the method comprising: providing a tiltrotor aircraft comprising atleast two propulsion systems and a driveshaft interconnected between thetwo propulsion systems; each of the propulsion systems comprising: anengine disposed at a fixed location relative to a wing member; a fixedgearbox; a spindle gearbox that is rotatable about a conversion axis; arotor mast rotatably coupled to the spindle gearbox; a quill shaftproviding torque transfer between the fixed gearbox and the spindlegearbox; and a torque measuring system associated with the quill shaft;providing a sensor associated with the quill shaft; transmitting datafrom the sensor to the torque measuring system; and determining, by thetorque measuring system, a torque value through the quill shaft withdata from the sensor.
 2. The method according to claim 1, wherein theconversion axis is perpendicular to a rotational axis of the rotor mast.3. The method according to claim 1, wherein the sensor is configured tomeasure a magnetic field of an element associated with the quill shaft,wherein the element creates a magnetic field upon a torsional deflectionof the quill shaft.
 4. The method according to claim 3, wherein thesensor is a transducer.
 5. The method according to claim 3, wherein theelement is a magnetoelastically active element.
 6. The method accordingto claim 1, further comprising: referencing a first magnet with a firstportion of the quill shaft, the first magnet being configured such thatrotation of the first portion of the quill shaft causes similar rotationof the first magnet; and referencing a second magnet with a second endportion of the quill shaft, the second magnet being configured such thatrotation of the second end portion of the quill shaft causes similarrotation of the second magnet.
 7. The method according to claim 6,wherein the step of referencing the first magnet with the first portionof the quill shaft is achieved by coupling a first end of a standpipe tothe first end portion of the quill shaft and coupling the first magnetto the second end of the standpipe.
 8. The method according to claim 1,wherein the torque measuring system comprising: a computer systemconfigured to determine the torque value through the quill shaft withdata from the sensor.
 9. The method according to claim 8, wherein thecomputer system is further configured to calculate the torque throughthe rotor mast.
 10. The method according to claim 8, wherein thecomputer system is further configured to calculate a torque efficiencyloss between the rotor mast and the quill shaft.
 11. The methodaccording to claim 1, further comprising: identifying an efficiency lossvalue between the quill shaft and the rotor mast; and using the torquevalue through the quill shaft and the efficiency loss value between thequill shaft and the rotor mast to determine the torque through the rotormast; wherein the determined torque through the rotor mast is used todetect operational loads transmitted through the rotor mast to improveaircraft operation.